Criminal behaviour by staff, including theft and illegal drugs, went unchallenged at Wales’ largest hospital, a report has found.

An “atmosphere of fear” in the surgical department of University Hospital of Wales meant staff did not raise concerns.

The report by Cardiff and Vale health board also found anaesthetic practitioners were not always in theatre for the whole operation, but instead were in the anaesthetic room on their phones or watching Netflix.

The health board apologised, saying it had taken action and implemented improvements, but also confirmed a separate review was under way into allegations staff allowed members of the public into the operating theatre to watch surgery.

Behaviour of surgery staff largely went unaddressed as some said they often worked through their breaks, so needed to take food and drink into the anaesthetic room.

It found staff felt belittled and there was a culture where swearing and outright criminal behaviour – including theft and illegal drugs found in a staff locker – went unchallenged.

The report found issues that compromised infection control as staff members of all groups were not wearing a mask properly, did not have bare arms below the elbow and were wearing jewellery or nail varnish.

The poor state of the hospital was also raised as repair and cleanliness was below expected standards, with several cases of pigeons being found in trauma theatres or on the theatre corridor.

The report found teams often worked against each other, impacting the efficiency of theatres and a failure to follow policies enabled behaviours to go unchecked, leading to people feeling let down and unsafe.

Health board bosses confirmed one person was caught with drugs prior to this investigation and it was reported to police, who did not bring charges.

That person is still working at the health board after a disciplinary process.

An anonymous complaint of racism was also made to management and the Nursing and Midwifery Council – an investigation was held and the person accused was suspended, but no further action was taken as there was insufficient evidence.

The reluctance of staff to speak up made complaints difficult to address, the health board said, which is why work was being done to change and improve the culture.

In a joint statement, the health board’s Suzanne Rankin and Paul Bostock said while the report was “very disappointing and concerning”, safety remained a top priority.

They added: “The health board will now consider the findings, recommended actions and implications of the service review as it develops a management response and a detailed action plan to make urgent improvements and address quality and safety issues.

“Colleagues directly involved in theatres will receive a copy of the report and will be supported by a series of face-to-face briefings with the chief operating officer and other senior colleagues.”

More than a third of theatre staff shared their experiences for the review, which began last summer and was conducted by two senior colleagues with no line management responsibility of theatres.

The investigation looked into 15 of the hospital’s 39 operating theatres, which bosses said were used to carry out 10,700 operations each year.

The majority of these, about 7,000, are emergency cases which are carried out 24/7, they added.